Polysaccharides or polysaccharide ethers, in particular cellulose ethers, are used in many different application systems where they are of variable significance. Depending upon the nature of the cellulose ether and the concentration and molecular weight thereof, the products have a thickening action in their various formulations and exhibit differing thixotropic and/or pseudoplastic properties, so in turn controlling processing characteristics which vary depending upon the area of application (for example, use in foodstuffs, pharmaceuticals, cosmetics and others). See, for example, Ullmann's Encyclopedia of Industrial Chemistry, vol. 5A, Verlag Chemie, Weinheim/New York, 1986.
In cement and gypsum renders, cellulose ethers, in particular methylcellulose mixed ethers, control water requirements and consequently the processing life and rendering yield. Water retention determines processing characteristics such as for example pliability, consistency, plasticisation, tendency to adhere to smoothing tools and combability as well as sag and slippage resistance and slurry formation. The use of cellulose ethers moreover controls adhesion to the substrate and ensures reliable curing.
In cement extrusion, it is important, inter alia, that, even at elevated pressures, the building material compositions or mixtures remain dimensionally stable and retain good mouldability and moreover have adequate water retention, even at relatively high temperatures of approx. 40-50° C. Many different cellulose ethers, in particular methylcellulose (mixed) ethers, are added to the building material mixtures in order to achieve this.
The cellulose ethers used in tile adhesives must provide an adequate thickening action (consistency) and water retention. They also distinctly improve adhesion to the substrate and sag resistance. Tile adhesives formulated with cellulose ethers must exhibit not only sufficiently high slippage resistance but also very good tensile bond strength under differing conditions to which the tiles are exposed, even under critical conditions (for example, exposure to elevated temperatures of 70° C., exposure to freeze-thaw cycles, exposure to water).
Important properties for use in filler compositions are mixing and thickening behaviour during processing of the filler compositions. Applicational properties, such as for example good workability and sag resistance, of the filler compositions are established by the nature of the cellulose ether used and the associated rheological profile. Sufficiently high water retention is necessary in order to avoid cracking during processing.
When cellulose ethers are used in aqueous coating systems, such as for example emulsion paints, silicone resin paints and silicate paints, it is desirable that such use be accompanied by good applicational properties of the paint or of the dried film (for example, low tendency to splash, good paint surface, good pigment dispersion, elevated resistance to washing and scrub resistance and others). The cellulose ethers should additionally be distinguished by improved thickening performance, good storage stability in the paint, simple processing and environmentally friendly application.